Method and system for 10GBASE-T start-up

ABSTRACT

Certain aspects for the start-up procedure of transceivers supporting higher data rates over twisted-pair copper cabling are provided for 10 Gbit/sec Ethernet links (10GBASE-T). During a PMA (physical medium attachment) training period of the start-up procedure, long PMA training frames are exchanged periodically between link partners. A significant portion of each PMA training frame consists of known pseudo random sequences simultaneously transmitted over four wire pairs. PMA training frames include an InfoField for exchanging parameters and control information between link partners. For example, the InfoField&#39;s payload comprises fields for indicating current transmit power backoff (PBO), next PBO, requested PBO, transition count, control information, and for communicating precoder coefficients. Information in InfoFields is repeated and is not necessary that a link partner decodes every InfoField. For example, by occasionally reading the transition count, a link partner can determine when a change in transmit PBO and/or a state transition is to occur.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This patent application is a continuation of U.S. patent applicationSer. No. 11/410,172 filed on Apr. 24, 2006, which application makesreference to, claims priority to, and claims benefit from U.S.Provisional Patent Application Ser. No. 60/722,677 filed on Sep. 30,2005.

The above referenced application is hereby incorporated herein byreference in its entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[Not Applicable]

MICROFICHE/COPYRIGHT REFERENCE

[Not Applicable]

FIELD OF THE INVENTION

Certain embodiments of the invention relate to networking. Morespecifically, certain embodiments of the invention relate to a methodand system for training 10 Gbit/sec Ethernet transceivers fortwisted-pair cabling (10GBASE-T) during a start-up procedure.

BACKGROUND OF THE INVENTION

As the number of devices connected to data networks increase and higherdata rates are required, there is a growing need for new transmissiontechnologies enabling higher transmission rates over existing coppercabling infrastructures. A current effort to that end is the developmentof a standard for 10 Gbit/sec Ethernet transmission over twisted-paircabling (10GBASE-T). The emerging 10GBASE-T physical layer (PHY)specification is intended to enable 10 Gbit/sec connections overtwisted-pair cabling at distances of up to 182 feet for existingcabling, and at distances of up to 330 feet for new cabling, forexample. To achieve full-duplex transmission at 10 Gbit/sec overfour-pair cabling, elaborate digital signal processing techniques areneeded to remove or reduce the effects of severe frequency-dependentsignal attenuation, signal reflections, near-end and far-end crosstalkbetween the four pairs, and external signals coupled into the four pairseither from adjacent transmission links or other external noise sources.Moreover, new cabling specifications are developed to diminishsusceptibility to external electro-magnetic interferences.

A pair of 10GBASE-T PHY transceivers on each side of a link mustinitially be trained during a start-up procedure to adapt transmitterand receiver settings to the specific characteristics of the link. Thestart-up procedure may include establishing initial synchronization,setting transmit power levels, adjusting echo and near-end crosstalkcancellers, adjusting equalizers, selecting and exchanging precodingcoefficients, etc. Elaborate start-up procedures are known in the art,for example those used in voiceband modems. Some start-up procedures areaimed at achieving relatively short start-up times. For lower-rate PHYtransceivers prior to 10GBASE-T, real-time execution of start-upspecific functions meeting the requirements of time-critical handshakeprocedures usually did not pose severe problems. For 10GBASE-T, wherestart-up time may not be a critical issue, minimizing the means requiredfor accomplishing start-up specific functions may be more important.Hence there is a need for a start-up procedure that permits performingsuch functions by shared hardware, firmware, or software at far lessthan real-time speed in exchange for a longer start-up time. Then onlyfunctions needed for sustained continuous data transmission, such aslong digital filters or decoders for error correction decoding, must berealized by highly efficient hardware that can perform these functionsin real time.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for 10 Gbit/sec Ethernet overtwisted-pair cabling (10GBASE-T) start-up, substantially as shown and/ordescribed in connection with at least one of the figures, as set forthmore completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a block diagram of a 10 Gbit/sec Ethernet over twisted-paircabling (10GBASE-T) link between a master link partner and a slave linkpartner, in accordance with an embodiment of the invention.

FIG. 2 shows a block diagram of an exemplary 10GBASE-T link partner, inaccordance with an embodiment of the invention.

FIG. 3 is a state diagram illustrating modes of operation in a 10GBASE-Tlink partner, in accordance with an embodiment of the invention.

FIG. 4 is a state diagram illustrating a start-up sequence that includesa physical medium attachment (PMA) training period, in accordance withan embodiment of the invention.

FIG. 5 depicts an exemplary exchange of PMA training frames betweenmaster and slave link partners, in accordance with an embodiment of theinvention.

FIG. 6 illustrates exemplary InfoField payloads, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in the start-upprocedure of the emerging physical layer specification 10BASE-T, whichis intended to become part of the IEEE 802.3 Ethernet standard.10GBASE-T transceivers will enable 10 Gbit/sec transmission overtwisted-pair copper cables. The specification provides for full-duplextransmission simultaneously over four pairs of ISO Class E or Class Fcables at a rate of 2.5 Gbit/sec per pair.

During IEEE 802.3 Auto Negotiation, the link partners agree on the typeof physical layer transmission to be used. Also, one transceiver assumesthe role of a Master and the other the role of a Slave. If 10GBASE-T hasbeen selected, the link partners then proceed to the 10GBASE-T start-upprocedure.

The 10GBASE-T start-up procedure is characterized by the followingfeatures. During an initial PMA (Physical Medium Attachment) trainingperiod, long PMA training frames are periodically transmitted over allfour pairs. The length of the PMA training frames may be 16 k symboltimes, for example. Each PMA training frame consists of a known pseudorandom sequence of binary modulation symbols. In addition, the framestransmitted over one of the four pairs in each direction comprise anInfoField, which is short compared to the length of the PMA trainingframes. The InfoFields are used for exchanging parameters and controlinformation between the link partners. Transmission is started by theMaster transceiver on all four pairs. After detecting the Master signalsand receiving an invitation to start transmission, the Slave transceiveralso starts to transmit on all four pairs.

Knowledge of the periodically transmitted binary sequences enables thereceiver sections of the link partners to acquire and maintain symboltiming and PMA frame synchronization throughout the entire PMA trainingperiod. For other purposes the known long sequences exhibit thecharacteristics of essentially random sequences.

The InfoFields convey control information of various types. For example,the InfoField's payload comprises fields for indicating current transmitPBO (power backoff) of the transmitting transceiver, next transmit PBOof the transmitting transceiver, requested PBO for the transceiver ofthe link partner, and a transition count. The InfoField's payloadcontains also fields for sending precoder coefficients, indicating theSNR margin in the receiver section of a transceiver, and other controlinformation. The transition count indicates the remaining number of PMAtraining frames, after which an announced change will occur. The changemay be a change in transmit PBO and/or or a transition to a next statein the state diagram of the transmitting transceiver. A link partner isnot required to decode every received InfoField, and is never requiredto react immediately to information received in InfoFields. For example,by only occasionally decoding an InfoField and reading the transitioncount therein, a link partner can determine when the announced change isto occur. Thus resources needed for performing a variety of start-upspecific functions can be allocated in transceivers with greatflexibility and without stringent real-time requirements.

FIG. 1 shows a block diagram of a 10 Gbit/sec Ethernet over twisted-paircabling (10GBASE-T) link between a master link partner and a slave linkpartner, in accordance with an embodiment of the invention. Referring toFIG. 1, there is shown a system 100 that comprises a master link partner102 and a slave link partner 104. The master link partner 102 and theslave link partner 104 communicate via a 4-wire unshielded twisted pair(UTP) cable 112. The master link partner 102 comprises a computer system106 a, a medium access control (MAC) controller 108 a, and a transceiver104 a. The slave link partner 104 comprises a computer system 106 b, aMAC controller 108 b, and a transceiver 110 b. Notwithstanding, theinvention is not limited in this regard.

The transceiver 110 a comprises suitable logic, circuitry, and/orprogram code that enables communication, for example, transmission andreception of data, between the master link partner 102 and a linkpartner, such as the slave link partner 104, for example. Similarly, thetransceiver 110 b comprises suitable logic, circuitry, and/or code thatmay enable communication between the slave link partner 104 and a linkpartner, such as the master link partner 102, for example. Thetransceivers 110 a and 110 b enable 10GBASE-T operations. The datatransmitted and/or received by the transceivers 110 a and 110 b isformatted in accordance with the well-known IEEE 802 LAN/MAN standards.

FIG. 2 shows a block diagram of an exemplary 10GBASE-T link partner, inaccordance with an embodiment of the invention. Referring to FIG. 2,there is shown a link partner 200 that comprises a transceiver 202, aMAC controller 204, a computer system 206, an interface 208, and a buscontroller interface 210. The transceiver 202 can be an integrateddevice that comprises a PHY block 212, a plurality of transmitters 214a, 214 c, 214 e, and 214 g, a plurality of receivers 214 b, 214 d, 214f, and 214 h, a memory 216, and a memory interface 218. The transceiver202 is the same as or substantially similar to the transceivers 110 aand 110 b described in FIG. 1. Similarly, the MAC controller 204, thecomputer system 206, the interface 208, and the bus controller 210 arethe same as or substantially similar to the respective MAC controllers108 a and 108 b, computer systems 106 a and 106 b, interfaces 114 a and114 b, and bus controller interfaces 116 a and 116 b described in FIG.1.

The PHY block 212 in the transceiver 202 comprises suitable logic,circuitry, and/or program code that enables operability and/orfunctionality of PHY layer requirements. The PHY block 212 communicateswith the MAC controller 204 via the interface 208. In one aspect of theinvention, the interface 208 may be configured to utilize a plurality ofserial data lanes for receiving data from the PHY block 212 and/or fortransmitting data to the PHY block 212, in order to achieve compatible10 Gb/sec operational speeds. The PHY block 212 is configured to operatein one or more of a plurality of communication modes, where eachcommunication mode implements a different communication protocol.

The transmitters 214 a, 214 c, 214 e, and 214 g comprises suitablelogic, circuitry, and/or program code that enables transmission of datafrom the link partner 200 to a link partner via the UTP cable 212 inFIG. 1, for example. The receivers 214 b, 214 d, 214 f, and 214 hcomprise suitable logic, circuitry, and/or program code that may enablereceiving data from a link partner by the link partner 200. Each of thefour pairs of transmitters and receivers in the transceiver 202correspond to one of the four wires in the UTP cable 212. For example,transceiver 214 a and receiver 214 b are utilized to communicate with alink partner via the first wire pair in the UTP cable 212. Similarly,transceiver 214 g and receiver 214 h are utilized to communicate with alink partner via the fourth wire pair in the UTP cable 212. In thisregard, each of the four transceiver/receiver pairs correspond to a 2.5Gbit/sec connection, for example.

FIG. 3 is a state diagram illustrating modes of operation in a 10GBASE-Tlink partner, in accordance with an embodiment of the invention.Referring to FIG. 3, there is shown a state diagram 300 that comprisesan auto-negotiation mode 302, a start-up mode 304, and a data mode 306.The PHY block 212 in the transceiver 202 described in FIG. 2 areutilized by a link partner to coordinate state or mode transitions whenestablishing a network connection with a link partner. During theauto-negotiation mode 302, a master link partner and a slave linkpartner determines the maximum connection speed that may be supportedfor communicating with each other.

When the auto-negotiation mode 302 is completed and 10GBASE-T has beenselected as a physical layer transmission method, the link partnerstransition to the 10GBASE-T start-up mode 304 where appropriate trainingsignals and/or control information are exchanged in order to establishthe 10 Gbit/sec network connection. In some instances, during thestart-up mode 304, certain conditions can arise that require the linkpartners to transition back to the auto-negotiation mode 302 anddetermine a new maximum connection speed.

When a network or link connection is properly established in thestart-up mode 304, the link partners will transition to the data mode306 where they communicate information. Upon termination of the networkconnection, the link partners transition back to the auto-negotiationmode 302. In some instances, during the data mode 306, certainconditions can arise that require the link partners to transition to thestart-up mode 304 and reestablish the network connection.

FIG. 4 is a state diagram illustrating a start-up sequence that includesa PMA training period, in accordance with an embodiment of theinvention. Referring to FIG. 4, there is shown a state diagram 400 thatcorresponds to changes in states of operation of the PHY block 212 whena network connection is established. When the auto-negotiation state 402is completed, a signal is generated to enable the PHY block 212 totransition from a PHY disabled state 404 to a PHY silent state 406.During the PHY silent state 406, the PHY block 212 remains silent, thatis, the PHY block 212 does not communicate with the link partner. Afterthe appropriate silence interval is completed, the operation of the PHYblock 212 transitions to a PMA train master state 408, if the linkpartner is configured as a master link partner. Alternatively, theoperation of the PHY block 212 transitions to a PMA train slave state410, if the link partner is configured as a slave link partner.

During the PMA train master state 408, the master link partner startssending PMA training frames to the slave link partner. When the masterlink partner is ready to receive PMA training frames from the slave linkpartner, it invites the slave link partner to transmit its own PMAtraining frames and waits for the slave link partner's PMA trainingframes.

The PMA training frames may be long, repetitive or periodic frames thatcomprise a pseudo random portion or sequence and an information field orInfoField, for example. The pseudo random portion may be generated fromseed values determined during the auto-negotiation state 402. The PMAtraining frames may be 16 k symbols in length and have a duration ofapproximately 20.48 μs, for example. The PMA training frames aremodulated using 2-level pulse amplitude modulation (2-PAM), for example.The InfoField portion of the PMA training frames comprises informationthat enables the Master and Slave link partners to train echo and/ornear-end crosstalk cancellers, to train receivers, and to establishappropriate transmitter power levels, for example. The contents of thepseudo random portion of PMA training frames shall be known while thecontents of the InfoFields vary in accordance with progress in thestart-up procedure. Processing of information in response of to receivedInfoFields need not be performed in real time.

During the PMA train slave state 410, the slave link partner conditionsits receiver section to receive PMA training frames and the InfoFieldstherein contained from the master link partner. When this isaccomplished and an invitation from the master link partner to starttransmission is received, the slave link partner starts transmission ofPMA training frames.

While operating in the PMA master or slave states, the link partnersensure that satisfactory transceiver operation with enoughsignal-to-noise ratio (SNR) margin is achieved for reliably decodingafter completion of the PMA training period physical coding sublayer(PCS) frames. This includes requesting through the requested transmitPBO field of InfoFields sent to the link partner that the link partnerswitches its transmit PBO setting to the requested value. By using thetransition count field in the InfoFields, the link partners announce toeach other when the change of their respective PBO settings willactually occur.

After completion of either the PMA train master state 408 or the PMAtrain slave state 410, the PHY block 212 proceeds to the PMA coefficientexchange state 412. During the PMA coefficient exchange state 412, thelink partners send and receive precoding coefficients via InfoFields. Inthis regard, the operations of the master and slave link partners aresymmetrical. For example, 64 decision feedback filter coefficients, 16coefficients for each of the four wire pairs in the UTP cable, may becommunicated to the link partner for later use for precoding, such asTomlinson-Harashima (TH) precoding, by the link partner during the PMAfine adjustment state 414 and onwards. After the exchange ofcoefficients is completed, the link partners announce by using thetransition count in the InfoFields to each other a transition from PMAcoefficient exchange state 412 to the PMA fine adjustment state 414.

During the PMA fine adjustment state 414 the coefficients received fromthe link partner are employed for sending additional PMA training framesnow with TH precoding. After the link partners have to completed andrefined adjustments necessary to establish the final link connection. Inthis regard, the PMA fine adjustment state 414 ensures proper receptionof TH precoded PMA training frames on both sides of the link and finalconvergence of all adaptive filters. When this is accomplished, the linkpartners announce by using the transition count in the InfoFields toeach other a transition from PMA fine adjust state 414 to the PCS teststate 416. The completion of the PMA fine adjustment state 414 alsocorresponds to the completion of the PMA training period.

During the PCS test state 416, the master and slave link partnersoperations are symmetric. Instead of PMA training frames the linkpartners send PCS frames using the final coding and modulation forsending data at 10 Gbit/sec bi-directionally over the link. For example,the PCS frames may be low-density parity-check (LDPC) coded with amapping of bits to higher-order modulation symbols from atwo-dimensional 128-point Double Square (128-DSQ) constellation, and theframes may be 320 ns in duration. In the PCS test state 416, onlyscrambled test data are transmitted, which can be distinguished fromuser data. Each link partner monitors its receiver performance. If afterthe determined time period satisfactory receiver performance isasserted, a link partner proceeds to the PCS data state 418. In thisstate, the link partners send user data from the transmit portion of theMAC interface and deliver user data to the receive portion of the MACinterface. If in the PCS test state 416 or in the PCS data state 418 alink partner detects an error situation, which may consists in toofrequent decoding failures, it transitions back to the PHY silent state406. As a result, the other link partner will also detect an errorsituation and transition back to the PHY silent state 406.

FIG. 5 depicts an exemplary exchange of PMA training frames betweenmaster and slave link partners, in accordance with an embodiment of theinvention. Referring to FIG. 5, there is shown a PMA training period 501that may be up to 2 sec in duration, for example. During the PMAtraining period 501, the master (M) and slave (S) link partners exchangePMA training frames. Regarding the master link partner, there is shown asequence of master PMA training (PMA TRN_(M)) frames 500 a transmittedto the slave link partner. Each PMA TRN_(M) frame 500 a comprises apseudo random portion 502 a and an InfoField (IF) 504 a. The start ofthe first PMA TRN_(M) frame 500 a corresponds to the start of the PMAtraining period 501. The end of the last PMA TRN_(M) frame 500 acorresponds to the end of the PMA training period 501 for the masterlink partner. After the end of the PMA training period 501, the masterlink partner begins PCS operation and transmits PCS frames 506 to theslave link partner during PCS operations in accordance with the statediagram given in FIG. 4.

Similarly, FIG. 5 shows a sequence of slave PMA training (PMA TRN_(s))frames 500 b transmitted to the master link partner. Each PMA TRN_(S)frame 500 b comprises a pseudo random portion 502 b and an IF 504 b. Thestart of the first PMA TRN_(S) frame 500 b occurs after the master clockis recovered from the received PMA TRN_(M) frames 500 a. The end of thelast PMA TRN_(S) frame 500 b corresponds to the end of the PMA trainingperiod 501 for the slave link partner. After the end of the PMA trainingperiod 501, the slave begins PCS operation and transmits PCS frames 508to the master link partner in accordance with the state diagram given inFIG. 4.

FIG. 6 illustrates exemplary InfoField payloads, in accordance with anembodiment of the invention. Referring to FIG. 6, there is shown anInfoField (IF) 600 that comprises a delimiter 602, an IF payload 604,and a cyclic redundancy check (CRC) 606. The delimiter 602 comprises aknown binary sequence. In some instances, the IF 600 may be implementedwithout a delimiter 602. The CRC 606 comprises information for verifyingthe contents of the IF payload 604, for example.

The IF payload 604 comprises a plurality of fields that may containinformation that may be utilized by the master and slave link partnersduring the PMA training period of the start-up procedure. In thisregard, there may be various configurations of fields in the IF payload604 based on the current state in the start-up procedure. For example,there is shown in FIG. 6 an IF payload 608 that comprises fields such ascontrol bits 610, current power backoff (PBO) 612, next PBO 614,requested PBO 616, further control bits 618, and transition counter 620.The control bits 610 and the further control bits 618 may be utilized toindicate the current state in the start-up procedure and the localreceiver's status for reliable decoding. The current PBO 612 field maybe utilized to indicate the current power backoff of the transmittinglink partner from a nominal maximum transmit power level. The next PBO614 field in combination with the transition count may be utilized toannounce to the link partner a change in the transmit PBO to the valuein the next PBO field. The requested PBO 616 field may be utilized torequest that the remote link partner sets the transmit PBO to arequested value.

The transition counter 620 field may be utilized to announce to theremote link partner a transition in the characteristics of the signal ofthe transmitting link partner. The transition counter 620 field may beset to a value that indicates the number of PMA frames after which thetransition will occur. The value in this field is decremented with eachsubsequent transmission of an InfoField 600 until the value zero isreached. In this regard, the link partner need not decode the InfoFieldof every PMA training frame. It suffices to read the InfoField onlyoccasionally to obtain the current value of the transition count andthus know when an announced change is to occur.

Also shown in FIG. 6 is an IF payload 628 that comprises fields such ascontrol bits 630, index of coefficients sent 632, index of coefficientsreceived 634, further control bits 636, and a group of N coefficientfields containing coefficient 1 638 to coefficient N 640. The controlbits 630 and the further control bits 636 may indicate the current statein the start-up procedure and the local receiver's status for reliabledecoding. The index of coefficients sent 632 field may indicate thegroup of N coefficients currently being transmitted to the link partnerin fields coefficient 1 638 to coefficient N 640. The index ofcoefficients received 634 field may acknowledge to the link partner upto which group of N coefficients the transmitting link partner hasalready correctly received coefficients. In this regard, for example,when the local link partner has received all coefficients from theremote link partner and the remote link partner acknowledges receptionof all coefficients, the bidirectional coefficient exchange is complete.The link partners may then announce a transition to the PMA fineadjustment state 414.

The approach described herein permits realizations of start-up specificfunction with great flexibility in non-real time.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least oneprogrammable computing system, or in a distributed fashion wheredifferent elements are spread across several interconnected computingelements. Any kind of computing system or other apparatus adapted forcarrying out the methods described herein is suited. A typicalcombination of hardware and software may be a general-purpose computersystem with a program for processing captured data and signal traces,and thus carrying out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method for setting up communication devices,the method comprising: transmitting, from a device, physical mediumattachment (PMA) training frames to a remote device during a trainingperiod, wherein: a majority portion of each of the transmitted PMAtraining frames is comprised of pseudo random known sequences that areutilized to establish transceiver operations for communication betweenthe device and the remote device; and the device and the remote deviceare communicatively coupled via a wired Ethernet link.
 2. The method ofclaim 1, wherein a remaining portion of each of the transmitted PMAtraining frames comprises exchanging parameters and control information.3. The method of claim 2, wherein the remaining portion of thetransmitted PMA training frames comprises fields for communicating aplurality of coefficients and associated index fields indicating whichcoefficients are currently being transmitted and which coefficients havealready been received.
 4. The method of claim 2, wherein the remainingportion of the transmitted PMA training frames comprises one or more ofa current power backoff (PBO) field, a next PBO field, a requested PBOfield, a transition count field, and at least one control field.
 5. Themethod of claim 1, comprising receiving, by the device, PMA trainingframes from the remote device during the training period, wherein amajority portion of each of the received PMA training frames iscomprised of pseudo random known sequences that are utilized toestablish transceiver operations for communication between the deviceand the remote device.
 6. The method of claim 5, wherein a remainingportion of the received PMA training frames comprises one or more of acurrent PBO field, a next PBO field, a requested PBO field, a transitioncount field, and at least one control field.
 7. The method of claim 6,comprising determining a power level change based on one or more of thecurrent PBO field, the next PBO field, and the requested PBO field. 8.The method of claim 6, wherein the transition count field indicates anumber of received PMA training frames after which a power level changeoccurs in a signal of the remote device or a number of received PMAtraining frames after which a state transition occurs in the remotedevice.
 9. The method of claim 6, wherein the received PMA trainingframes are communicated to the device by the remote device after theremote device recovers a master clock during the training period. 10.The method of claim 1, comprising programming coefficients in a precoderin the device during the training period.
 11. A system for setting upcommunication devices, the system comprising: a device that is operableto transmit physical medium attachment (PMA) training frames to a remotedevice during a training period, wherein a majority portion of each ofthe transmitted PMA training frames is comprised of pseudo random knownsequences that are utilized to establish transceiver operations forcommunication between the device and the remote device; and the deviceis operable to be communicatively coupled to the remote device via awired Ethernet link.
 12. The system of claim 11, wherein a remainingportion of each of the transmitted PMA training frames comprisesexchanging parameters and control information.
 13. The system of claim12, wherein the remaining portion of the transmitted PMA training framescomprises fields for communicating a plurality of coefficients andassociated index fields indicating which coefficients are currentlybeing transmitted and which coefficients have already been received. 14.The system of claim 12, wherein the remaining portion of the transmittedPMA training frames comprises one or more of a current power backoff(PBO) field, a next PBO field, a requested PBO field, a transition countfield, and at least one control field.
 15. The system of claim 11,wherein: the device is operable to receive PMA training frames from theremote device during the training period; and a majority portion of eachof the received PMA training frames is comprised of pseudo random knownsequences that are utilized to establish transceiver operations forcommunication between the device and the remote device.
 16. The systemof claim 15, wherein a remaining portion of the received PMA trainingframes comprises one or more of a current PBO field, a next PBO field, arequested PBO field, a transition count field, and at least one controlfield.
 17. The system of claim 16, wherein the device is operable todetermine a power level change based on one or more of the current PBOfield, the next PBO field, and the requested PBO field.
 18. The systemof claim 16, wherein the transition count field indicates a number ofreceived PMA training frames after which a power level change occurs ina signal of the remote device or a number of received PMA trainingframes after which a state transition occurs in the remote device. 19.The system of claim 16, wherein the received PMA training frames arecommunicated to the device by the remote device after the remote devicerecovers a master clock during the training period.
 20. The system ofclaim 11, wherein the device comprises a precoder and is operable toprogram coefficients in the precorder during the training period.